The role of the computer core is to provide computer resources - hardware, software and staff - that are needed by the various research projects and by the program project as a whole. Current efforts by the computer core center on the development of software systems for planning and delivering conformal radiation treatments. We describe each of these systems in turn: 1) A first generation three-dimensional radiation treatment planning (3DRTP) system has been developed at MSKCC and is currently in clinical use. It enables the user, from an input set of CT images, to outline structures of interest, set up beams, perform dose calculations, and display the results for evaluation. Additional features necessary for conformal therapy planning, including multileaf collimation, are presently being incorporated into this system. Concurrently, we are developing a second generation system with many new features, which will operate on high-performance RISC-based workstations. 2) The computer core staff is collaborating with Scanditronix to develop and improve software that will facilitate delivery of computer-controlled, segmental conformal treatments, using the MM50 Microtron. The computer core software system (called the Conformal Treatment Verification, Delivery and Recording, or CTVDR System) will provide access to the patient database and communicate with the Scanditronix MM50 Therapy Software to transmit machine parameters for delivering treatments, verify machine settings and record treatments. Patient setup and actual delivery of treatment is under the control of the MM50 Therapy Software. In addition we discuss patient safety during computer-controlled radiation delivery, in particular, the procedures and system safeguards that are to be implemented to ensure integrity of the data used to deliver treatments, and to protect against possible collisions during computer-controlled motions. We also describe quality assurance procedures with regard to the above software systems.